Input devices allow a user to place information into a computer. The most common input devices are probably keyboards, mice, graphics tablets and joysticks. The joystick is particularly useful in activities requiring hand-eye coordination such as game playing and computer training programs. Computer training programs are used to teach people to handle a variety of tasks such as flying airplanes, controlling satellites, operating ship loading equipment and performing surgical operations.
When many of these activities are performed in the actual situation there is a resistive feedback to the performer. For instance, in flying an airplane the control stick may require more force to move when the stick is moved to extreme positions. Or in performing an operation it may require more force to cut through some tissues than it does for others.
Therefore, it may be useful to have a system in which the joystick has a variable resistance to movement with that resistance under computer control. The computer can then cause the joystick to have a resistance to movement for each program activity that matches the resistance to be found in the real life activity.
The following U.S. Patents are of interest in the joystick art; U.S. Pat. Nos. 4,127,841, 4,156,130, 4,200,780, 4,216,467, 4,414,438, 4,491,325 4,509,383 4,533,899, 4,590,339, 4,685,678, 4,748,441, 4,766,423, 4,769,517 4,800,721 4,814,682, 4,820,162, 4,870,389 and 4,879,556.